<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            /* 设置一个边框 */
            /* border: 10px red solid; */
            /* 1.设置边框的粗细 */
            border-width: 2px;
            /* 2.设置边框的颜色 */
            border-color: aqua;
            /* 3.设置边框的样式：实线:solid 虚线：dashed 点线:dotted */
            border-style: solid;
            border-style: dashed;
            border-style: dotted;
            /* 属于外边框 */
            /* border: 1px solid #000; */
        }
    </style>
</head>

<body>
    <div>1</div>
</body>

</html>